Aerodynamic systems and fairings with fairing caps

ABSTRACT

A fairing assembly adapted to control flow proximate to a vehicle wheel, the fairing assembly having an aerodynamic outer surface to direct flow. The fairing assembly comprises a fairing having a fairing outboard surface. The assembly further comprises a fairing cap coupled to the fairing to cover at least a portion of the fairing outboard surface.

RELATED APPLICATIONS

This application claims the benefit of priority under 35 USC § 119(e) toU.S. Provisional Patent Application No. 62/524,528,” entitled“Aerodynamic System and Adjustable Fairings,” filed Jun. 24, 2017, byJoshua Butler and Kyle Walker and to U.S. Provisional Patent ApplicationNo. 62/538,791, entitled “Aerodynamic System and Adjustable Fairings,”filed Jul. 30, 2017, by Joshua Butler and Kyle Walker, both of which arefully incorporated by reference herein in their entireties for allpurposes.

TECHNICAL FIELD

This disclosure relates to aerodynamic systems for vehicles. Moreparticularly, this disclosure relates to aerodynamic fairings forvehicles. Even more particularly, embodiments relate to aerodynamicfairings for large vehicles such as tractor trailers.

BACKGROUND

Large vehicles such as semitrailer trucks may easily travel severalthousand miles each month, including on highways and other routes whichallow for higher speeds. Poor aerodynamics cause a decrease in fueleconomy and an increase in operating cost.

Various types of aerodynamic systems have been devised for reducingvehicle drag, including fairings—that is, external panels or structuresadded to vehicles to increase streamlining and reduce drag—that arepositioned to control airflow. U.S. Pat. Nos. 9,027,983 and 9,663,157,both of which are fully incorporated herein by reference for allpurposes, describe aerodynamic fairing systems that include a quarterfender fairing assembly, a middle or tandem fairing assembly and a rearfairing assembly. The quarter fender fairing assembly mounts forward ofthe truck tractor's non-steered wheels, the tandem (or middle) fairingassembly mounts to the tractor between the tandem wheels and the rearfairing assembly mounts to the tractor behind the rear tandem wheels.Each fairing assembly includes a mounting arm that mounts to the tractorframe and one or more panels that mount to the support arm. The panelsare shaped to produce a desired aerodynamic flow.

In practice, the manner in which fairings mount to support arms leavesthe mounting hardware exposed when the vehicle is viewed from the side.In addition to poor aesthetics, the exposed mounting hardware may leadto poor airflow at the mounting hardware. As another shortcoming, themounting hardware may get damaged over time by road debris.

SUMMARY OF THE DISCLOSURE

Embodiments described herein provide systems and methods for improvingthe aerodynamics of vehicles, including large vehicles that are commonlyseen pulling cargo trailers on highways, and which are generallyreferred to as “semis,” “18-wheelers,” “tractor trailers,” and the like.Embodiments may also be beneficial on other vehicles as well.

One embodiment comprises a fairing assembly adapted to control flowproximate to a vehicle wheel, the fairing assembly having an aerodynamicouter surface to direct flow in, for example, a rearward angle or otherdesired angle. The fairing assembly comprises a fairing having a fairingoutboard surface. The assembly further comprises a fairing cap coupledto the fairing to cover at least a portion of the fairing outboardsurface. According to one embodiment, the fairing may define a hardwareopening running from an outboard side through the fairing, the hardwareopening adapted to accommodate mounting hardware used to mount thefairing to a support structure. The fairing cap can be adapted to coverthe hardware opening from the outboard side.

According to one embodiment, the fairing cap comprises a fairing capoutboard surface. The fairing cap outboard surface can cooperate withthe fairing outboard surface to provide the aerodynamic outer surface ofthe fairing assembly. The fairing cap may have an inner side surfaceshaped to conform to an outboard surface of the fairing. For example,the fairing cap may be shaped to fit in a recess, such as an inset, inthe outboard surface of the fairing so that the fairing cap may bepositioned in the recess. The outboard surface of the fairing cap andthe outboard surface of the fairing can cooperate to provide a fairingassembly outer surface.

In another embodiment, the fairing cap forms a duct adapted to directflow. More particularly, in one embodiment, the fairing cap acts incooperation with the outboard surface of the fairing to create the duct.For example, the fairing cap may comprise an upper fairing cap wall, alower fairing cap wall and a sidewall extending from the upper fairingcap wall to the lower fairing cap wall. The fairing cap may be coupledto the fairing in a manner such that the sidewall has an inner sidesurface (inboard surface) that is spaced from and faces the fairingoutboard surface. The fairing cap walls and fairing can cooperate toform the duct between the fairing cap and fairing.

The fairing cap may comprise a hinge. A portion of the fairing cap isrotatable about the hinge to reveal a portion of the outboard surface ofthe fairing. For example, the portion of the fairing cap may berotatable to reveal the portion of the fairing through which mountinghardware passes.

The fairing cap may be coupled to the fairing in a variety of manners.The fairing cap may be adhered to the outboard surface of the fairing.In addition or in the alternative, the fairing cap may be captured in arecess of the fairing by a geometric feature. In one embodiment, thefairing may include geometric features to capture the inboard end of thefairing cap upper and lower walls. In one embodiment, the fairing capmay attach to the mounting hardware that is used to mount the fairing tothe support structure.

According to one embodiment, the fairing and fairing cap are formed ofdifferent materials. For example, the fairing cap may be formed of amore rigid material than the fairing. Even more particularly, in oneembodiment, the fairing is molded from one or more polymers and thefairing cap is separately formed of a more rigid polymer or a metal.

Another embodiment comprises a method for mounting a wheel fairing. Themethod may include mounting a fairing to a support arm where the fairinghas a fairing outboard surface with a hardware opening to accommodatemounting hardware. The method may further include coupling a fairing capto the fairing to cover the hardware opening from the outboard side andto form a fairing assembly. The fairing assembly may have an aerodynamicouter surface to direct flow in a rearward angle. The method may furtherinclude positioning the fairing assembly proximate to a wheel of avehicle.

Coupling the fairing cap to the fairing can include placing the fairingcap in a recess defined by the fairing outboard surface. For example,the fairing cap may be placed in a recess (e.g., an inset) defined bythe fairing outboard surface. The fairing cap may have an inner sidesurface shaped to conform to the fairing outboard surface. Coupling thefairing cap to the fairing may include adhering the fairing cap to theoutboard surface of the fairing with an adhesive. Coupling the fairingcap to the fairing may include catching a portion of the fairing capwith a geometric feature of the fairing. Coupling the fairing cap to thefairing comprises coupling the fairing cap to the fairing such that afairing cap outboard surface cooperates with the fairing outboardsurface to provide the aerodynamic outer surface. Coupling the fairingcap to the fairing may comprise forming a duct configured to direct airflow.

BRIEF DESCRIPTION OF THE DRAWINGS

For a more complete understanding of the present disclosure and theadvantages thereof, reference is now made to the following descriptiontaken in conjunction with the accompanying drawings in which likereference numerals indicate like features and wherein:

FIG. 1A is a diagrammatic representation of one embodiment of anaerodynamic system;

FIG. 1B is a diagrammatic representation of another view of theaerodynamic system of FIG. 1A;

FIG. 2A is an exploded view of one embodiment of a fairing assembly;

FIG. 2B is a perspective view of the embodiment of FIG. 2A;

FIG. 3A is an exploded view of another embodiment of a fairing assembly;

FIG. 3B is perspective view of the embodiment of FIG. 3A;

FIG. 4A is a diagrammatic representation of another embodiment of anaerodynamic system;

FIG. 4B is a diagrammatic representation of another view of theaerodynamic system of FIG. 4A;

FIG. 5A is an exploded view of another embodiment of a fairing assembly;

FIG. 5B is a perspective view of the embodiment of FIG. 5A;

FIG. 5C is a top view of the embodiment of FIG. 5A;

FIG. 6A is an exploded view of another embodiment of a fairing assembly;

FIG. 6B is perspective view of the embodiment of FIG. 6A;

FIG. 7A is a view of another embodiment of a fairing assembly;

FIG. 7B is another view of the embodiment of FIG. 7A;

FIG. 8A is a view of another embodiment of a fairing assembly;

FIG. 8B is another view of the embodiment of FIG. 8A;

FIG. 9 is an exploded view of another embodiment of a fairing assembly;

FIG. 10 is a sectional view of one embodiment of a connection system forconnecting a fairing cap to mounting hardware.

DETAILED DESCRIPTION

The disclosure and various features and advantageous details thereof areexplained more fully with reference to the exemplary, and thereforenon-limiting, embodiments illustrated in the accompanying drawings anddetailed in the following description. Descriptions of known startingmaterials and processes may be omitted so as not to unnecessarilyobscure the disclosure in detail. It should be understood, however, thatthe detailed description and the specific examples, while indicating thepreferred embodiments, are given by way of illustration only and not byway of limitation. Various substitutions, modifications, additionsand/or rearrangements within the spirit and/or scope of the underlyinginventive concept will become apparent to those skilled in the art fromthis disclosure.

Embodiments described herein provide systems and methods for improvingthe aerodynamics of vehicles, including large vehicles that are commonlyseen pulling cargo trailers on highways, and which are generallyreferred to as “semis”, 18-wheelers,” “tractor trailers” and the likeand may be beneficial on other vehicles as well. Embodiments may beparticularly suited for reducing drag, reducing or otherwise controllingthe generation or distribution of spray/splash or improving thestability of large vehicles in an airstream.

FIG. 1A illustrates a side view of an aerodynamic system mounted to atruck tractor 100 and FIG. 1B illustrates another view of theaerodynamic system mounted to the truck tractor 100. A portion oftrailer 102 is also depicted. In the illustrated embodiment, the trucktractor 100 includes forward tandem tires 106 and rear tandem tires 108.The aerodynamic system includes a quarter fender 110 mounted to asupport 111 in front of front tandem wheels 106, a tandem or middlefairing assembly 112 mounted to the tractor 100 by support 114 thatpasses between the tandem tires 106, 108 and a rear fairing assembly 116mounted to the tractor 100 by a support 118 behind the rear tandemwheels 108. The mounting hardware to mount fairing assemblies 112 and116 to supports 114, 118 is protected from the outboard side by fairingcaps.

A standard quarter fender in a standard location is shown installed inthe figures. An aerodynamic quarter fender fairing may also be used withthe aerodynamic system (instead of or in addition to the standardquarter fender). Examples of aerodynamic quarter fender fairings aredescribed in U.S. Pat. No. 8,814,253, entitled “Aerodynamic QuarterFender Assembly and Construction Method,” by inventors Joshua Butler, etal., which is fully incorporated as part of this disclosure for allpurposes. Quarter fender 110 and fairing assemblies 112, 116 are adaptedto mount proximate to the wheels of a vehicle to control airflowproximate to the wheels. Wheel covers 120, which mount directly to thewheels, may provide a substantially smooth surface flush with an outersidewall of the tires or may provide another aerodynamic profile.Examples of aerodynamic wheel covers are described in U.S. patentapplication Ser. No. 13/545,100, entitled “Aerodynamic Wheel Covers andMounting Assemblies,” by inventors Joshua Butler, et al., which is fullyincorporated as part of this disclosure for all purposes.

In operation, airflow is directed around forward tandem tires 106 by aquarter fender fairing 110, passes by a first tire, passes over theoutboard surface of middle fairing assembly 112, passes by a rear tandemtire 108 and passes over the outboard surface of rear fairing assembly116. The aerodynamic system can facilitate a smooth transition behindtires 108 and extend the airflow in a direction substantially parallelwith the outer sidewall of the tandem tires or direct the airflow out(i.e., away from the frame rail). Additionally, embodiments of anaerodynamic system may direct airflow parallel with the ground, in adownward direction or an upward direction as desired.

FIG. 2A is an exploded view of an embodiment of a rear fairing assembly200 and FIG. 2B is an assembled view of fairing assembly 200. Rearfairing assembly 200 may be an example of rear fairing assembly 116.Rear fairing assembly 200 comprises fairing 202 and a fairing cap 220.

In general, fairing 202 and fairing assembly 200 have a generally thinlateral profile and a much larger longitudinal profile, providing asurface area to promote streaming. The outboard surface of fairingassembly 200 may form an aerodynamic outer surface that providesattached flow for longitudinal air flow (air flow streaming back as thevehicle moves forward) and can direct flow in a longitudinal angle suchas parallel to the longitudinal axis of the vehicle, primarily back andinwards or back and outwards. Preferably, the fairing assembly has asufficient projected surface area (in view from the side of the vehicle)to promote attached flow.

Rear fairing 202 comprises a mounting portion 210 and an outer peripheryportion 212. In the embodiment illustrated, outer periphery has ac-shape about mounting portion 210. However, outer periphery portion 212may have other shapes. Mounting portion 210 provides a mounting area forrear fairing 202 and can include features, such as ribs or otherfeatures, to increase the rigidity of rear fairing 202 around themounting area. Rear fairing assembly 200 mounts to a support structurethat, in turn, mounts to the vehicle frame. The support structure mayinclude a support arm (e.g., support arm 118), adapter plate or otherstructures. Examples of support arms include, but are not limited tosupport arms for mud flap fairings as described in U.S. Pat. Nos.9,027,983 and 9,663,157. Furthermore, according to one embodiment, rearfairing 202 can be a mud flap fairing as described in U.S. Pat. Nos.9,027,983 and 9,663,157. In the illustrated embodiment, mounting portion210 includes a hardware opening running from the outboard surface ofmounting portion 210 and inboard through fairing 202 to accommodate themounting hardware used to mount the fairing assembly to a supportstructure. For example, fairing 202 includes an array of fasteneropenings 206 through which fasteners, such as bolts, screws or otherfasteners, may be inserted so that rear fairing 202 can be attached tothe support structure. The openings may be spaced so that rear fairing202 can be attached to a fairing adapter plate as described, forexample, in U.S. Pat. Nos. 9,027,983 and 9,663,157. In addition or inthe alternative, the mounting fasteners and associated fastener openingsmay also be located on a sidewall of the fairing, the inner surface ofthe fairing, or another location on the fairing.

The outboard surface of outer periphery portion 212 may be in the sameplane as, inset from or be more outboard from the outboard surface ofmounting portion 210. In the embodiment illustrated, the outboardsurface of mounting portion 210 is inset from the outboard surface ofouter periphery portion 212 to form an inset. Thus, in the illustratedembodiment, the outboard ends of fastener openings 206 are located in arecess formed by the shape of the outboard surface of rear fairing 202.

Rear fairing cap 220 can be coupled to rear fairing 202 to cover, fromthe outboard side, the fasteners that hold rear fairing 202 to thesupport structure. In the embodiment illustrated, fairing cap 220comprises a sidewall 226 and peripheral wall 228 that extends outboardfrom the sidewall 226. In the embodiment illustrated, the inner sidesurface of fairing cap 220 that faces the outboard surface of fairing202 is shaped to conform to the outboard surface of fairing 202 atmounting section 210 (e.g., to fit the shape of the recess so thatfairing cap 220 can be positioned in the recess).

Fairing cap 220 may be attached to rear fairing 202 in a variety ofmanners. In one embodiment, the inner side surface of cap 220 is adheredto rear fairing 202. In another embodiment, rear fairing 202 and fairingcap 220 include geometric features (e.g., tongue and groove fittings,indents, detents, catches or other features) to allow fairing cap 220 toattach to rear fairing 202. Other types of interference fit methodsknown in the art used to couple plastic parts together, plastic andmetal parts together or other parts may also be employed. For example,during assembly, wall 228 may flex to allow the top, bottom and lowerportions of the outboard cap edge 224 to fit past and then snap-fit tothe inboard side of a lip 208 disposed about the top, rear and bottomoutboard edges of the recess. In another embodiment, the heads of thefasteners used to attach rear fairing 202 to the support arm may havefeatures to accept the clips and cap 220 may comprise clips or geometricfeatures that project inboard to be received by the heads of thefasteners. The clips may be inserted in the heads of the fasteners tocouple cap 220 to the support arm and thus form fairing assembly 200.

Fairing assembly 200, when assembled, comprises a center portion 230about which outer periphery portion 212 is disposed. The center portion230 is formed by mounting portion 210 of fairing 202 and cap 220.Through the selection of shape or materials, the outer periphery may bemore flexible than the center portion 230 to absorb impacts from theground or trailer. According to one embodiment, for example, fairing 202can be formed such that outer periphery portion 212 is more flexiblethan mounting portion 210. In addition or in the alternative, fairingcap 220 may formed of a more rigid material than fairing 202 and thusprovide increased stiffness to the fairing assembly, including but notlimited to providing stiffness at the center portion 230.

Fairing assembly 200 has a leading edge 240 and a trailing edge 242.Leading edge 240 may have a curved portion for accommodating the profileof a wheel. The fairing assembly 200 may be shaped to have a continuousaerodynamic outboard surface from leading edge 240 to trailing edge 242to promote attached flow across the surface. More particularly, theoutboard surface of the fairing cap 220 and fairing 202 can cooperate toprovide the aerodynamic outer surface of fairing assembly 200. Accordingto one embodiment, the fairing assembly may be shaped to have anoutboard surface with a first, more inboard portion 250, a transitionarea 252, and a second, more outboard, surface portion 254. In theillustrated embodiment, the first surface portion 250 is formed as arelatively flat surface, transition area 252 is formed as a discrete orstepped transition zone transitioning from first surface portion 250 tosecond surface portion 254, and second surface portion 254 is formed asan angled or curved outward surface. The fairing assembly may includemore or fewer surfaces, areas or zones as needed and in some embodimentsmay have flat outer surfaces. Curves may be compound or simple, andstepped areas may include more than one step.

FIG. 3A is an exploded view of an embodiment of a middle fairingassembly 300 and FIG. 3B is an assembled view of fairing assembly 300.Middle fairing assembly 300 can be an example of middle fairing assembly112.

Middle fairing assembly 300 comprises a middle fairing 302 and a fairingcap 320. Middle fairing assembly 300 may be shaped to ensure air flowstays outboard of the tires on the rear tandem axle (i.e., may reduce orprevent air flow from entering the space between the front axle tiresand the rear axle tires). The middle fairing assembly 300 may alsocontain other aerodynamic features such as vents, ribs, or otherfeatures, for reducing drag and controlling splash and spray, orproviding ventilation for dissipating heat.

In FIG. 3A, middle fairing 300 comprises a center portion 310, an upperportion 312 and a lower portion 314. Center portion 310 provides amounting area for middle fairing 302 and can include features, such asribs or other features, to increase the rigidity of middle fairing 302around the mounting area. The outboard surface of one or more of theupper and lower portions 312, 314 may be in the same plane as, insetfrom or be more outboard from the outboard surface of center portion310. In the embodiment illustrated, the outboard surface of centerportion 310 is inset from the outboard surface at upper portion 312 andlower portion 314 to form a recess.

Middle fairing assembly 300 mounts to a support structure that, in turn,mounts to the vehicle frame and spans between tires on a front tandemaxle and tires on a rear tandem axle. The support structure may includea support arm (e.g., support arm 114), adapter plate or other supportstructure. Examples of support arms include, but are not limited tomiddle fairing support arms described in U.S. Pat. Nos. 9,027,983 and9,663,157, both of which are fully incorporated herein by reference forall purposes. Further, middle fairing 302 may be a middle fairing formedaccording to U.S. Pat. Nos. 9,027,983 and 9,663,157. Center portion 310includes a hardware opening running from the outboard surface of centerportion 310 and inboard through fairing 302 to accommodate the mountinghardware used to mount the fairing assembly to a support structure. Forexample, center portion 310 includes an array of fastener openings 306through which fasteners, such as bolts, screws or other fasteners, maybe inserted so that middle fairing 302 can be attached to the supportarm. The openings may be spaced so that the middle fairing can beattached to a fairing adapter plate as described, for example, in U.S.Pat. Nos. 9,027,983 and 9,663,157. The outboard ends of fasteneropenings 306 may be located in a recess (e.g., a pocket or other recess)formed by the shape of the outboard surface of middle fairing 302. Inaddition or in the alternative, the mounting fasteners and associatedfastener openings may also be located on a sidewall of the fairing, theinner surface of the fairing, or another location on the fairing.

Fairing cap 320 can be coupled to middle fairing 302 to cover, from theoutboard side, the fasteners that hold middle fairing 302 to the supportarm. In the embodiment illustrated, fairing cap 320 comprises a sidewall326 and upper and lower walls 322, 324 that extend outboard from thesidewall 326. The inner surface of fairing cap 320 that faces theoutboard surface of fairing 302 is shaped to conform the outboardsurface of fairing 302 at middle section 310 (e.g., to fit the shape ofthe recess so that fairing cap 320 can be positioned in the recess).

Fairing cap 320 may be attached to middle fairing in a variety ofmanners. In one embodiment, the inboard surface of cap 320 is adhered tomiddle fairing 302. In another embodiment, middle fairing and fairingcap 320 may include geometric features (e.g., tongue and groovefittings, indents, detents, catches or other features) to allow fairingcap 320 to attach to middle fairing 302. For example, during assembly,walls 322, 324 may flex to allow the top and bottom outboard edges 326,328 to fit past and then snap-fit to the inboard side of lips 318disposed about the top, rear and bottom outboard edges of the recess. Inanother embodiment, the heads of the fasteners used to attach middlepanel 302 to the support arm may have features to accept the clips andcap 320 may comprise clips that project inboard to be received by theheads of the fasteners. The clips may be inserted in the heads of thefasteners to couple cap 320 to the support arm and thus form fairingassembly 300.

Fairing assembly 300, when assembled, comprises a center portion 330formed by center portion 310 and cap 320, an upper portion 312 and alower portion 314. Through the selection of shape or materials, theupper portion 312 and lower portion 314 may be more flexible than thecenter portion 330 to absorb impacts from the ground or trailer.According to one embodiment, for example, fairing 302 can be formed suchthat upper portion 312 and lower portion 314 are more flexible thancenter portion 310. In addition or in the alternative, fairing cap 320may formed for a more rigid material than fairing 302 and thus provideincreased stiffness at center portion 330.

In the embodiment illustrated in FIG. 3B, fairing assembly 300 forms anaerodynamic outboard surface between a leading edge 340 and a trailingedge 342 that promotes attached rearward flow (when the vehicle ismoving forward). More particularly, the outboard surfaces of the fairingcap 320 and fairing 302 cooperate to provide the aerodynamic outersurface of fairing assembly 300. In some cases, the outer surface maydirect the flow rearward or rearward and slightly inward or outward. Theouter surface may have a variety of profiles including flat, curvedoutward toward the rear, or other profile. According to one embodiment,leading edge 340 may be curved to substantially conform to the shape ofa tire forward of assembly 300 and trailing edge 342 may have a curvedshape to conform to the shape of tire to the rear of assembly 300.

FIG. 4A illustrates a side view of another embodiment of an aerodynamicsystem mounted to a truck tractor 400 and FIG. 4B illustrates anotherview of the aerodynamic system mounted to the truck tractor 400. Aportion of trailer 402 is also depicted. In the illustrated embodiment,the truck tractor 400 includes tandem front tires 406 and rear tires408. The aerodynamic system includes a standard quarter fender 410mounted to a support 411 in front of front tandem tires 406, a middlefairing assembly 412 mounted to the tractor 400 by a support that passesbetween the tandem tires 406, 408 and a rear fairing assembly 416mounted to the tractor 400 by a support 418 behind the rear tandem tires408. The mounting hardware to mount fairing assemblies 412 and 416 tothe supports is protected from the outboard side by fairing caps thatform air ducts to control air flow.

A standard quarter fender in a standard location is shown installed inthe figures. An aerodynamic quarter fender fairing may also be used withthe aerodynamic system (instead of or in addition to the standardquarter fender). Examples of aerodynamic quarter fender fairings aredescribed in U.S. Pat. No. 8,814,253, entitled “Aerodynamic QuarterFender Assembly and Construction Method,” by inventors Joshua Butler, etal., which is fully incorporated as part of this disclosure for allpurposes. Quarter fender 410 and fairing assemblies 412, 416 are adaptedto mount proximate to the wheels of a vehicle to control airflowproximate to the wheels. Wheel covers 420, which mount directly to thewheels, may provide a substantially smooth surface flush with an outersidewall of the tires or may provide another aerodynamic profile.Examples of aerodynamic wheel covers are described in U.S. patentapplication Ser. No. 13/545,100, entitled “Aerodynamic Wheel Covers andMounting Assemblies,” by inventors Joshua Butler, et al., which is fullyincorporated as part of this disclosure for all purposes.

In operation, airflow is directed around forward tandem tires 406 by aquarter fender fairing (if utilized), passes by a first tire, passesover the outboard surface of middle fairing assembly 412 and through theduct of middle fairing assembly 412, passes by a rear tandem tire 408and passes over the outboard surface of rear fairing assembly 416 andthrough the duct of rear fairing assembly 416. The aerodynamic systemcan facilitate a smooth transition behind tires 408 and extend theairflow in a direction substantially parallel with the outer sidewall ofthe tandem tires or direct the airflow out (i.e., away from the framerail). Additionally, embodiments of an aerodynamic system may directairflow parallel with the ground, in a downward direction or an upwarddirection as desired.

FIG. 5A is an exploded view of an embodiment of a rear fairing assembly500 comprising a fairing 502 and a fairing cap 520, FIG. 5B is anassembled view of fairing assembly 500 and FIG. 5C is a top view offairing assembly 500. Rear fairing assembly 500 may be an example ofrear fairing assembly 416.

In general, fairing 500 and fairing assembly 502 have a generally thinlateral profile and a much larger longitudinal profile, providing asurface area to promote streaming. The outboard surface of fairingassembly 500 may form an aerodynamic outer surface that providesattached flow for longitudinal air flow (air flow streaming back as thevehicle moves forward) and can direct flow in a longitudinal angle suchas parallel to the longitudinal axis of the vehicle, primarily back andinwards or back and outwards. Preferably, the fairing assembly has asufficient projected surface area (in view from the side of the vehicle)to promote attached flow.

Rear fairing 502 comprises a mounting area for rear fairing 502 and caninclude features, such as ribs or other features, to increase therigidity of rear fairing 502 around the mounting area. Rear fairingassembly 500 mounts to a support structure that, in turn, mounts to thevehicle frame. The support structure may include a support arm (e.g.,support arm 418), adapter plate or other structures. Examples of supportarms include, but are not limited to support arms for mud flap fairingsas described in U.S. Pat. Nos. 9,027,983 and 9,663,157, both of whichare fully incorporated herein by reference for all purposes.Furthermore, according to one embodiment, rear fairing 502 can be a mudflap fairing. In the illustrated embodiment, mounting portion 510includes a hardware opening running from the outboard surface ofmounting portion 510 and inboard through fairing 502 to accommodate themounting hardware used to mount the fairing assembly to a supportstructure. For example, rear fairing 502 includes an array of fasteneropenings 506 through which fasteners, such as bolts, screws or otherfasteners, may be inserted so that rear fairing 502 can be attached tothe support structure. The openings may be spaced so that rear fairing502 can be attached to a fairing adapter plate as described, forexample, in U.S. Pat. Nos. 9,027,983 and 9,663,157. In addition or inthe alternative, the mounting fasteners and associated fastener openingsmay also be located on a sidewall of the fairing, the inner surface ofthe fairing, or another location on the fairing.

Rear fairing cap 520 can be coupled to rear fairing 502 to cover, fromthe outboard side, the fasteners that hold rear fairing 502 to thesupport arm. In the embodiment illustrated, rear fairing cap comprisesan upper wall 522, a lower wall 524 and an outboard sidewall 526extending from upper wall 522, and lower wall 524 and rear fairing 502includes geometric features 508 that capture the inboard ends of walls522, 524, such as edges behind which the ends of walls 522, 524 snap.Several non-limiting examples of geometric features are discussed ingreater detail below with respect to FIGS. 7A, 7B, 8A and 8B.

When assembled, inner surface of sidewall 526 is spaced from the facingoutboard surface 510 of rear fairing 502 to create an air duct 530between rear fairing 502 and cap 520. The duct 530 may have a desiredshape. For example, in FIG. 5A and FIG. 5B duct 530 narrows from frontto back. In other embodiments, however, duct 530 may have other shapes.The inner surface of cap 520 or outboard surface 510 may include ribs orother features to form multiple channels from front to rear in the duct530.

Fairing assembly 500 has a leading edge 540 and a trailing edge 542.Leading edge 540 has a curved portion for accommodating the profile of awheel. Fairing 502 may be shaped to have a continuous aerodynamicoutboard surface 510 from leading edge 540 to trailing edge 542 topromote attached flow across the surface. The outboard surface 510 andinboard surface of sidewall 526 can be shaped to create a duct 530 thatinterfaces with the airflow and controls the airflow in a desirablemanner. Moreover, the outboard surface 550 of cap 520 can also be shapedto provide an aerodynamic surface. 5C shows a top view of rear fairingillustrating how the duct 530 may be configured at a different angle orcurvature from the fairing, and how the duct may provide for an inletarea that is different from the outlet area.

FIG. 6A is an exploded view of an embodiment of a middle fairingassembly 600 comprising a middle fairing 602 and a fairing cap 620 andFIG. 6B is an assembled view of fairing assembly 600. Middle fairingassembly 600 can be an example of middle fairing assembly 412. Middlefairing assembly 600 may ensure air flow stays outboard of the tires onthe rear tandem axle (i.e., may reduce or prevent air flow from enteringthe space between the front axle tires and the rear axle tires). Themiddle fairing assembly 600 may also contain other aerodynamic featuressuch as vents, ribs, and other features, for reducing drag andcontrolling splash and spray, or providing ventilation for dissipatingheat.

Middle fairing assembly 600 mounts to a support structure, in turn,mounts to the vehicle frame and spans between tires on a front tandemaxle and tires on a rear tandem axle. The support structure may includea support arm, adapter plate or other structures. Examples of supportarms include, but are not limited to middle fairing support armsdescribed in U.S. Pat. Nos. 9,027,983 and 9,663,157, both of which arefully incorporated herein by reference for all purposes. Fairing 602includes a hardware opening running from the outboard surface of fairing602 and inboard through fairing 602 to accommodate the mounting hardwareused to mount the fairing assembly to a support structure. For example,fairing 602 includes an array of fastener openings 606 through whichfasteners, such as bolts, screws or other fasteners, may be inserted sothat middle fairing 602 can be attached to the support structure. Theopenings may be spaced so that the middle fairing can be attached to afairing adapter plate as described in U.S. Pat. Nos. 9,027,983 and9,663,157. In addition or in the alternative, the mounting fasteners andassociated fastener openings may also be located on a sidewall of thefairing, the inner surface of the fairing, or another location on thefairing.

Middle fairing cap 620 can be coupled to middle fairing 602 to cover,from the outboard side, the fasteners that hold middle fairing 602 tothe support arm. In the embodiment illustrated, middle fairing capcomprises an upper wall 622, a lower wall 624, and an outboard sidewall626 extending from upper wall 622 and lower wall 624 and fairing 602includes geometric features 608 sized to receive and capture the inboardends of upper wall 622 and lower wall 624. Several non-limiting examplesof geometric features are discussed in greater detail below with respectto FIGS. 7A, 7B, 8A and 8B.

When assembled, the inner surface of sidewall 626 is spaced from thefacing outboard surface 610 of middle fairing 602 to create an air duct630 between rear fairing 602 and cap 620. The duct 630 may have adesired shape. The inner surface of cap 620 or outboard surface 610 mayinclude ribs or other features to form multiple channels in the duct 630from front to rear.

Fairing assembly 600 includes a leading edge 640 and a trailing edge642. According to one embodiment, leading edge 640 may be curved tosubstantially conform to the shape of a tire forward of assembly 600 andtrailing edge 642 may have a curved shape to conform to the shape oftire to the rear of assembly 600. Fairing 602 forms an aerodynamicoutboard surface 610 between leading edge 640 and trailing edge 642 thatpromotes attached rearward flow (when the vehicle is moving forward). Insome cases, the outer surface 610 may direct the flow rearward orrearward and slightly inward or outward. The outer surface may have avariety of profiles including flat, curved outward toward the rear, orother profile. Moreover, the outboard surface 610 of fairing 602 andinner surface of sidewall 626 can be shaped to create a duct 630 thatinterfaces with the airflow and controls the airflow in a desirablemanner.

FIG. 7A and FIG. 7B illustrate a section view of one embodiment of afairing assembly 700 having a fairing 702 and fairing cap 720. Fairingcap 720 may cooperate with fairing 702 to form a duct or gap between thefairing and the fairing cap may be sealed. Fairing 702 includesgeometric features, in this case catches 708, to secure fairing cap 720.During assembly, the fairing cap upper wall 722 and fairing cap lowerwall 724 can be flexed toward each other to pass catches 708. Theinboard ends of a fairing cap upper wall 722 and fairing cap lower wall724 can return outward to snap in place to the inboard side of catches708. Features 708 represent one embodiment of features 508, 608 that canallow a ducted cap to be assembled with a fairing without tools.

FIG. 8A and FIG. 8B illustrate section views of one embodiment of afairing assembly 800 having a fairing 802 and fairing cap 820. Fairingcap 820 may cooperate with fairing 802 to form a duct or sealed gap 830.Faring 802 includes geometric features, in this case slots 808. Duringassembly, the fairing cap upper wall 822 and fairing cap lower wall 824can be flexed toward each other to pass through openings 808. Theinboard ends of a fairing cap upper wall 822 and fairing cap lower wall824 can return outward snap in place inboard of fairing surface 810.Features 808 represent one embodiment of features 508, 608 that canallow a ducted cap to be assembled with a fairing without tools.

FIG. 9 is an exploded view of an embodiment of a middle fairing assembly900 comprising a middle fairing 902 and a fairing cap 920. Middlefairing assembly 900 may ensure air flow stays outboard of the tires onthe rear tandem axle (i.e., may reduce or prevent air flow from enteringthe space between the front axle tires and the rear axle tires). Themiddle fairing assembly 900 may also contain other aerodynamic featuressuch as vents, ribs, or other features, for reducing drag andcontrolling splash and spray, or providing ventilation for dissipatingheat.

In FIG. 9, middle fairing 900 comprises a center portion 910, an upperportion 912, a lower portion 914, a front portion 911 and a rear portion915. The outboard surface of one or more of the upper and lower portions912, 914 may be in the same plane as, inset from or be more outboardfrom the outboard surface of center portion 910. From front-to-rear, theoutboard surface of center portion 910 slopes outward to provide a wedgeshape. The center of center portion is inset to provide a mounting area916 having an array of fastener openings for fasteners used to mountfairing 902 to a support structure. The mounting area 916 could also beconfigured as an opening in the fairing which may in turn be covered bythe fairing cap in order to, for example, reduce total material usage.

In the example of FIG. 9, the support structure includes a mountingplate 918, which can be mounted, in turn, to a support arm or otherstructure. The outboard ends of the fastener openings are thus locatedin a recess (e.g., a pocket or other recess) formed by the shape of theoutboard surface of middle fairing 902. The mounting area for middlefairing 902 and can include features, such as ribs or other features, toincrease the rigidity of middle fairing 902 around the mounting area.

Fairing cap 920 can be coupled to middle fairing 902 to cover thefasteners that hold middle fairing 902 to the mounting plate. In theembodiment illustrated, fairing cap comprises a sidewall 922, and rearwall 924, upper wall 926 and lower wall 928 that form a pocket. Theinner surface of fairing cap 920 is shaped to conform the outboardsurface of fairing 902 at middle section 910 so that middle section 910can nest in fairing cap 920.

Fairing cap 920 may be attached to middle fairing in a variety ofmanners. In one embodiment, the rear wall 924 of fairing cap includesfastener openings that align with fastener openings in the rear wall 904of middle section 910. In addition, fastener openings in cap 920 canalign with faster openings 918 through the outboard surface of fairing902. Fasteners can thus be used to fasten cap 920 to fairing 910.

According to one embodiment, fairing cap 902 may incorporate a livehinge (e.g., along transition 950 between the sidewall 922 and rear wall924) so that, by removing fasteners 919, an operator can open the cap toreveal mounting area 916.

Fairing assembly 900, when assembled, comprises a center portion formedby center portion 910 and cap 920, an upper portion 912 and a lowerportion 914. Through the selection of shape or materials, the upperportion 912, front portion 911, rear portion 915 and lower portion 914may be more flexible than the center portion to absorb impacts from theground, trailer, tires, or other objects. According to one embodiment,for example, fairing 902 can be formed such that upper portion 912 andlower portion 914 are more flexible than center portion 910. In additionor in the alternative, fairing cap 920 may formed for a more rigidmaterial than fairing 902 and thus provide increased stiffness at thecenter portion of the assembled fairing or more overall stiffness to thefairing assembly.

In the embodiment illustrated in FIG. 9, fairing assembly 900 forms anaerodynamic outboard surface between a leading edge and a trailing edgethat promotes attached rearward flow (when the vehicle is movingforward). In this example, the outer surface directs the flow rearwardand outward. According to one embodiment, the leading edge may be curvedto substantially conform to the shape of a tire forward of assembly 900and the trailing edge may have a curved shape to conform to the shape oftire to the rear of assembly 900.

FIG. 10 illustrates one embodiment of a fairing 1002 mounted to asupport structure 1004. In the embodiment illustrated, fairing 1002 ismounted using a bolt 1006 and nut 1008. Bolt 1006 includes a radialflange spaced from the fastener's head 1012 to create an annulardepression 1014 between head 1012 and flange 1010. A fairing capincludes a clip 1020 that projects inboard from the inner surface of thefairing cap. The clip includes fingers 1022 that have a radially inwardprotruding parts 1024 (e.g., hook, stud, detent, bead). The fingers 1022are adapted to deflect briefly during the attachment operation and thenreturn inward so that the protruding parts 1024 catch in depression1014. While only one fastener is illustrated, it will be appreciatedthat multiple fasteners may be used to mount a fairing 1002.

As will be appreciated from the foregoing discussion, a cap may be usedin combination with an aerodynamic quarter fender, wheel cover, centertandem fairing, or rear tandem fairing to: 1) conceal mounting hardware;2) allow the use of more desirable material properties for the fairingsuch as those which may be more flexible, durable, or have other desiredcharacteristics while using the cap to provide additional structuralsupport; 3) provide improved aerodynamics by covering openings in thefairing or creating a duct which allows the cap as well as the fairingoutboard surface to interface with the airflow and control the airflowin a desired manner; 4) provide a surface which can be painted; or 5)permit combinations of designs to be used (i.e. multiple different capscan be used with the same fairing). Other advantages may be obtained aswell.

It can be noted that an aerodynamic system may employ different types ofcaps. For example, the middle assembly may use a ducted cap (e.g., cap620) while the rear fairing assembly does not. In another embodiment,the rear fairing assembly may use a ducted cap (e.g., cap 520) while themiddle fairing does not.

The shape, size, materials, stiffness, and other characteristics of afairing (e.g., fairing 202, 302, 502, 602, 702, 802, 902) and fairingcap (e.g., fairing cap 220, 320, 520, 620, 720, 820, 920) may beselected to provide desired aerodynamics; minimize splash/spray; provideclearance with wheels to prevent rubbing/damage; provide clearance fromtop (trailer) contact to prevent damage; clearance from bottom/road(ground) contact to prevent damage; universal fit to fit differenttrucks that have different wheel sizes/spacing, frame heights; rigidityor structure, especially to provide increased rigidity in areas of therear fairing assembly that are used for mounting or that are unlikely tocome into contact with the wheels, trailer, or ground, for example andincreased flexibility and resiliency in areas that are likely to comeinto contact with the wheels, trailer, or ground, for example. A fairingassembly may be curved and sized for use by itself or in combinationwith other fairing assemblies, quarter fenders, or wheel covers.

Fairings and fairing caps are preferably manufactured of one or moredurable materials, such as polyurethane, which can absorb frequentimpacts and deflections of the material. Preferred materials formanufacturing a fairing include plastics, metals, and composites. Adeflectable, resilient, and wearable material such as TPO, TPV, TPE,Santoprene, or polyurethane may be desired, especially for regions ofthe part that may contact a trailer, ground, or wheels. Some materialsor manufacturing processes that may provide a part with a lower density,such as low density polyurethane, blow-molding, or rotational molding,for example, may be desired such that the part is less likely to causeadditional damage if it is damaged or dislodged from the vehicle, forexample. According to one embodiment, the fairing (e.g., fairing 202,302, 502, 602, 702, 802, 902) is formed of a more flexible plastic andfairing cap (e.g., fairing cap 220, 320, 520, 620, 720, 820, 920) isformed of a more rigid plastic or metal, such as aluminum.

A fairing cap may be attached to a fairing using a variety of methods. Afairing cap may be attached permanently or removably, with or withoutthe use of tools, and with or without the need to modify the geometry ofany of the parts being joined. A fairing cap may be attached to panel byadhesive, removable clips, molded-in clips. Attaching a fairing cap to afairing may include clipping the fairing cap into the fairing in a waythat requires flexing one of the parts.

Support structures for fairing assemblies may include support arms,adapter plates and other structures. Support arms may use a spring orother attachment to allow deflection of a fairing assembly. Deflectionof the fairing assembly may allow a person to access components behindthe assembly, and may also absorb energy from tire blowouts, impacts orother debris. According to one embodiment, the arm may use a two-sidedspring attachment to also allow deflection of a fairing in relation tothe arm. In another embodiment, the arm may be fixed at the vehicle end,but the fairing adapter may be spring mounted to allow the fairing todeflect relative the arm. Multiple hangers having spring attachmentshaving one-sided (vehicle side or fairing side) or two-sided springattachments may be used to mount multiple fairings or to support asingle larger fairing. In some cases, some fairings may be coupled toarms having spring attachments while others are coupled to arms that arefixed or a single fairing may be coupled to one or more arms havingspring attachments and to one or more fixed arms. Multiple fairings mayalso be coupled to the same arm (e.g., inboard and outboard of a mudflap or elsewhere). In other embodiments a substantially larger fairingmay be used or one or more of the fairings shown may be combined into asingle fairing.

According to one embodiment, a fairing support arm may have anadjustable length. Embodiments of an adjustable length hanger may allowthe hanger length to be set in any desired range, depending on vehicle.Adjustable and fixed length arms may use a spring attached and have avariety of form factors. In some embodiments the arms may be straight.In others, the arms may be angled at the end (e.g., “shorty” hangers). Asupport arm may mount to a vehicle frame in a manner that allows theposition of the arm to be selectable.

According to one embodiment, an assembly base may include a connectionsystem that accommodates various hole patterns in a frame rail or otherportion of a vehicle so that the base may be used with different holeconfigurations. In another embodiment, the base may include an adapterthat allows the base to be mounted in one or more positions orrotational orientations.

In one embodiment, the arm may be a mud flap hanger arm. A rear fairing(e.g., fairing 202, 502) may mount to the mud flap hanger and bepositioned outboard of the mud flap. In other embodiments, a fairing maybe integral with a mud flap. Embodiments may also include a middlefairing hanger arm and middle fairing. The middle fairing hanger mayhave an adjustable length to accommodate various tire sizes andconfigurations, and may be deflectable as well.

A fairing (e.g., fairing 202, 302, 502, 602, 702, 802, 902) may bemounted to the end of the arm using an adapter that is coupled to orintegral with the arm. According to one embodiment, the adapter mayallow the horizontal, vertical or rotational position of the fairing tobe selected. According to one embodiment, the adapter may include anadapter plate and a second plate. The second plate may be an end plateof an arm, a plate, a fixed or other plate coupled to a standard mudflap hanger or other hanger. The adapter plate may be coupled to thesecond plate in a number of selectable positions to adjust the mountingposition of the fairing.

In some embodiments, a fairing assembly (e.g., fairing assembly 110,112, 116, 200, 300, 410, 412, 416, 500, 600, 700, 800, 900) may beprovided with mechanisms for controlling splash and spray while alsoreducing aerodynamic drag (for example, perforations, fluid atomizingfeatures, fluid flow directing features such as ribs, fluid trapping orre-directing features, etc.). A fairing may be formed as a single bodyor it may be assembled, such as with a structural center portion forsupport with deflectable material attached to the outer edges of thecenter portion. A fairing cap be formed as a single body or it may beassembled.

According to one embodiment, the fairing or fairing assembly may have avariety of shapes. For example, the leading edge of the fairing assemblyor fairing may be straight or curved and the outer surface of thefairing may flat, angled or curved outward, angled or curved inward orsome combination thereof to promote desired aerodynamic flow. Thefairing or fairing assembly may have symmetric design to fit either sideof the vehicle in a desired position, including positions that areangled inward or outward.

A fairing cap may cover a larger or smaller area of a fairing thatillustrated in the example embodiments. In some cases the fairing capmay cover the entire lower portion, upper portion, forward portion, rearportion, or middle portion of the fairing. A fairing cap can cover oneor more sidewalls or edges of the fairing. Moreover, a fairing cap mayextend to cover a portion of the inner surface of the fairing as well.In some embodiments, more than one fairing cap may be used per fairing.

Although the invention has been described with respect to specificembodiments thereof, these embodiments are merely illustrative, and notrestrictive of the invention. The description herein of illustratedembodiments is not intended to be exhaustive or to limit the inventionto the precise forms disclosed herein (and in particular, the inclusionof any particular embodiment, dimensions, feature or function is notintended to limit the scope to such embodiment, feature or function).Rather, the description is intended to describe illustrativeembodiments, features and functions in order to provide a person ofordinary skill in the art context without limiting the invention to anyparticularly described embodiment, feature or function. While specificembodiments and examples are described herein for illustrative purposesonly, various equivalent modifications are possible within the spiritand scope of this disclosure, as those skilled in the relevant art willrecognize and appreciate. As indicated, these modifications may be madein light of the foregoing description of illustrated embodiments and areto be included within the spirit and scope of the invention. Thus, whilethe invention has been described herein with reference to particularembodiments thereof, a latitude of modification, various changes andsubstitutions are intended in the foregoing disclosures, and it will beappreciated that in some instances some features of embodiments of theinvention will be employed without a corresponding use of other featureswithout departing from the scope and spirit of the invention as setforth. Therefore, many modifications may be made to adapt a particularsituation or material to the essential scope and spirit of theinvention.

As used herein, the terms “comprises,” “comprising,” “includes,”“including,” “has,” “having” or any other variation thereof, areintended to cover a non-exclusive inclusion. For example, a process,product, article, or apparatus that comprises a list of elements is notnecessarily limited to only those elements but may include otherelements not expressly listed or inherent to such process, product,article, or apparatus. Further, unless expressly stated to the contrary,“or” refers to an inclusive or and not to an exclusive or. For example,a condition A or B is satisfied by any one of the following: A is true(or present) and B is false (or not present), A is false (or notpresent) and B is true (or present), and both A and B are true (orpresent). As used herein, a term preceded by “a” or “an” (and “the” whenantecedent basis is “a” or “an”) includes both singular and plural ofsuch term, unless clearly indicated otherwise (i.e., that the reference“a” or “an” clearly indicates only the singular or only the plural).Also, as used in the description herein, the meaning of “in” includes“in” and “on” unless the context clearly dictates otherwise.

Additionally, any examples or illustrations given herein are not to beregarded in any way as restrictions on, limits to, or expressdefinitions of, any term or terms with which they are utilized. Insteadthese examples or illustrations are to be regarded as being describedwith respect to one particular embodiment and as illustrative only.Those of ordinary skill in the art will appreciate that any term orterms with which these examples or illustrations are utilized encompassother embodiments as well as implementations and adaptations thereofwhich may or may not be given therewith or elsewhere in thespecification and all such embodiments are intended to be includedwithin the scope of that term or terms. Language designating suchnon-limiting examples and illustrations includes, but is not limited to:“for example,” “for instance,” “e.g.,” “in one embodiment,” and thelike. Furthermore, any dimensions, materials or other suchcharacteristics are provided by way of example and not limitation.

Reference throughout this specification to “one embodiment,” “anembodiment,” or “a specific embodiment,” or similar terminology meansthat a particular feature, structure, or characteristic described inconnection with the embodiment is included in at least one embodimentand may not necessarily be present in all embodiments. Thus, respectiveappearances of the phrases “in one embodiment,” “in an embodiment,” or“in a specific embodiment,” or similar terminology in various placesthroughout this specification are not necessarily referring to the sameembodiment. Furthermore, the particular features, structures, orcharacteristics of any particular embodiment may be combined in anysuitable manner with one or more other embodiments. It is to beunderstood that other variations and modifications of the embodimentsdescribed and illustrated herein are possible in light of the teachingsherein and are to be considered as part of the spirit and scope of theinvention.

Furthermore, the characterization of any feature as “optional” herein isprovided by example and is not intended to and should not be read toimply that other features not characterized as optional are not alsooptional in various embodiments.

In the description herein, numerous specific details are provided, suchas examples of components and/or methods, to provide a thoroughunderstanding of embodiments of the invention. One skilled in therelevant art will recognize, however, that an embodiment may be able tobe practiced without one or more of the specific details, or with otherapparatus, systems, assemblies, methods, components, materials, parts,and/or the like. In other instances, well-known structures, components,systems, materials, or operations are not specifically shown ordescribed in detail to avoid obscuring aspects of embodiments of theinvention. While the invention may be illustrated by using a particularembodiment, this is not and does not limit the invention to anyparticular embodiment and a person of ordinary skill in the art willrecognize that additional embodiments are readily understandable and area part of this invention.

What is claimed is:
 1. A fairing assembly adapted to couple to avehicle, the assembly comprising: a fairing, the fairing having afairing outboard surface; and a fairing cap coupled to the fairing to atleast partially cover at least a portion of the fairing outboardsurface, the fairing assembly having an aerodynamic outer surfaceadapted to direct flow.
 2. The fairing assembly of claim 1, wherein thefairing cap has an inboard surface shaped to conform to an outboardsurface of the fairing.
 3. The fairing assembly of claim 2, wherein thefairing cap is adhered to the outboard surface.
 4. The fairing assemblyof claim 2, wherein the fairing cap is captured in a recess of thefairing by a geometric feature.
 5. The fairing assembly of claim 1, thefairing cap comprising a fairing cap outboard surface that cooperateswith the fairing outboard surface to provide the aerodynamic outersurface.
 6. The fairing assembly of claim 1, wherein the fairing andfairing cap are formed of different materials.
 7. The fairing assemblyof claim 1, further comprising mounting hardware to mount the fairing toa support structure, wherein the fairing cap is coupled to the fairingby attachment to the mounting hardware.
 8. The fairing assembly of claim1, wherein the fairing cap comprises a hinge, wherein a portion of thefairing cap is rotatable about the hinge to reveal the at least aportion of the outboard surface of the fairing.
 9. The fairing assemblyof claim 1, wherein the fairing cap and fairing cooperate to form aduct.
 10. The fairing assembly of claim 9, the fairing cap comprising:an upper fairing cap wall; a lower fairing cap wall; and a sidewallextending from the upper fairing cap wall to the lower fairing cap wall,the sidewall having an inboard surface that is spaced from and faces thefairing outboard surface to form the duct.
 11. The fairing assembly ofclaim 10, the upper fairing cap wall and lower fairing cap wall eachcomprising an inboard end and the fairing comprising geometric featuresto capture the inboard ends of the upper fairing cap wall and the lowerfairing cap walls.
 12. The fairing assembly of claim 1, wherein thefairing comprises a rear fairing.
 13. The fairing assembly of claim 1,wherein the fairing comprises a middle fairing.
 14. A wheel fairingmethod comprising: mounting a fairing to a support arm, the fairinghaving a fairing outboard surface; coupling a fairing cap to the fairingto cover at least a portion of the outboard surface and to form afairing assembly, the fairing assembly having an aerodynamic outersurface adapted to direct flow; and positioning the fairing assemblyproximate to a wheel of a vehicle.
 15. The method of claim 14, whereincoupling the fairing cap to the fairing further comprises placing thefairing cap in a recess defined by the fairing outboard surface, whereinthe fairing cap has an inner surface shaped to conform to the fairingoutboard surface.
 16. The method of claim 15, wherein coupling thefairing cap to the fairing comprises adhering the fairing cap to theoutboard surface of the fairing.
 17. The method of claim 14, whereincoupling the fairing cap to the fairing comprises catching a portion ofthe fairing cap with a geometric feature of the fairing.
 18. The methodof claim 14, coupling the fairing cap to the fairing comprises couplingthe fairing cap to the fairing such that a fairing cap outboard surfacecooperates with the fairing outboard surface to provide the aerodynamicouter surface.
 19. The method of claim 13, wherein coupling the fairingcap to the fairing comprises coupling the fairing cap to the fairing toform a duct.
 20. The method of claim 13, wherein the fairing cap is morerigid than the fairing.